iPod My ipod says it wont update album art. please help!

i spent two hours getting album art onto my ipod and when i go to the options and check 'display album art on ipod' and hit OK, it optimizes it, but then an error message appears and tells me that my ipod could not be updated! can anyone explain this or help me fix it? its really bugging me.

i have a Windows iPod BTW.

thanks!